Sensitive relay mechanism



Aug. 17, 1943. B. cYR

SENSITIVE RELAY MECHANISM Filed Oct. 6, 1941 TEMPERATURE RESJPQNSVE RE5\STANCE Fig. 1

Fig.5 i313 Fig.4- v

WL M m m n w m fi Patented Aug. 17, 1943 UNITED STATES PATENT OFFICE SENSITIVE RELAY MECHANISM Application October 6, 1941, Serial No. 413,789

13 Claims.

The present invention relates to a sensitive relay mechanism and particularly to that type of mechanism wherein the operation of a motor is controlled in accordance with the position of a pointer of a delicate galvanometer.

Such mechanism usually includes a device for periodically clamping the galvanometer pointer. Each time the pointer is clamped, a member is moved into engagement with the pointer, and a switch mechanism is then operated in accordance with the position obtained by the member. When such a device is used to control a motor, the switch arrangement usually operates the motor in one direction or the other, depending upon the deflection of the galvanometer from a center position. With such mechanism it is customary to tilt a member in accordance with the position of a galvanometer needle and thereafter move said member through a fixed path. A switch mechanism, which is accordingly tilted, cooperates with a pair of fixed contacts to energize the motor in one direction or the other for a given period of time depending upon the time of engagement of the contacts as said member moves in said path. With such structure it is seen that it is necessary to have flexible contact means so as to relieve the strain in the mechanism.

It is therefore an object of the present invention to provide a sensitive relay mechanism with a novel strain release mechanism whereby the contact mechanism or associated structure will not be strained as the contacts are made for different lengths of time.

Another object is to provide a, strain release mechanism wherein one or the other of a plurality of contacts may be made and pushed back without unduly straining the other contact or other associated structure.

Further objects and advantages of the present invention will be in part apparent or pointed out in the accompanying specification and claims taken in view of the accompanying drawing, in which Figure l is a diagrammatic showing of my invention applied to a heat control system,

Figure 2 is a detailed side View of the strain release mechanism mounted upon the operator therefor,

Figures 3 and 4 are views of my strain release mechanism in two or its active positions, and

Figure 5 is a view of a part of the contact operator embodying a modification of the strain release mechanism.

Figure 1 illustrates a system for controlling the supply of heating fluid to a radiator ID in accordance with the temperature of the space I l in which the radiator I0 is located. A heating fluid which may be, for example, steam or hot water, is supplied to the radiator l0 through a supply pipe 12. This fluid after losing its heat, flows out of the radiator l0 through a return pipe I3. The supply of fluid to the radiator l0 through the pipe I2 is controlled by a valve I 4. The valve I4 is operated by a control mechanism generally indicated at $5 which includes a rack i6 mounted on the valve stem and cooperating with a pinion l1. Supported by the rack I6 is a slider 18, which is moved across the slidewire resistance [9 in accordance with the position of the Valve. The pinion I1 is driven by a motor 20, through a gear train schematically shown at 2|. The motor 28 is provided with a pair of windings 22 and 23 which drive the motor in opposite directions. The operation of the motor 20 is controlled by a bridge circuit generally indicated at 24 whose output is amplified by a sensitive relay mechanism 25.

The bridge circuit 24 is supplied with electrical energy from a suitable source, shown in the drawing as a battery so, connected to the input terminals 3! and 32, by conductors 33 and 34 respectively.

The upper left-arm of the bridge, as appears in the drawing, includes a fixed resistor 35, and a. variable resistor 36. This arm of the bridge connects the input terminal 38 with an output terminal 31. The variable resistor 36 is provided so that the temperature at which the bridge will control may be adjusted.

The upper right arm of the bridge includes a resistor element 40, of nickel or some other material having an appreciable temperature coeificient of resistance. Although the system will be described as though the element 4&3 had a positive temperature coeflicient, it will be readily apparent to those skilled in the art that an element having a negative temperature coefficient could be used with equal facility. One end of resistance element 40 is connected to the input terminal 3| through a conductor 4!, and the other end of resistance element 40 is connected to the lower terminal of the slidewire resistance [9 by a wire 42. The upper right arm of the bridge circuit 24 also includes that part of the slidewire resistance [9 between its lower terminal, and the point of contact of slider [8 along the resistance wire l9. This point of contact is numbered 43 in the drawing and serves as one of the output terminals of the bridge circuit 24.

. nal 31 by a conductor 46.

The lower right arm of the bridge circuit 24 includes a conductor 50, a fixed resistance 6!, a

conductor 52, and that portion of the slidewire resistance I9 between its upper terminal and the output terminal 43.

The output circuit of bridge 24 may be traced from the output terminal 31 to the movable output terminal 43. This output circuit includes a conductor 53, a coil 54 of a galvanometer generally indicated at 55, and a conductor 56 connected to the slider I8.

The coil 94 is mounted between the poles of the permanent magnet'60, and is attached to a pointer 6| which is deflected from a neutral position in accordance with the magnitude and direction-of the current flowing through the coil 54. The pointer 6| moves parallel to a bar 62, against which it is periodically clamped by a clamping lever 63, pivoted at 64, and operated by a cam 66 acting against a cam follower 66 on the end of clamping lever 63 at the opposite side of pivot '64 from the portion which engages the pointer M. The cam follower 66 is biased for engagement with the cam 65 by a spring 61.

The cam 65 is continuously rotated by a motor I connected through gears II and 12, the latter being attached to a shaft 13 on which the cam 65 is fixed. Also 'fixed on the shaft 13 is another cam I4. The can" acts against a cam follower 76 mounted on a lateral projection of a supporting arm 11, which is mounted on a fixed pivot -8I. The arm 11 is biased by a spring 88 so that the follower 16 engages the surface of the cam I4.

Pivotally mounted, as at 82, on the arm 11 is a switch operator 83. The switch operator 83 is provided with a long vertical extension 84 which is adapted to move transversely throug the path of movement of the pointer 6i. This witch operator 83 is biased for counter-clockwise rotation about the pivot 82 by a spring 85. Counter-clockwise rotation of the operator 83 with respect to the arm 11 is limited by a stop 86 which extends forwardly from the member 11. This stop 86 is arranged to engage a lower arm of the switch operator 83.

Duringcertain portions of the switching cycle rotation of the switch operator 83 is prevented by a brake member 90 which i biased into engagement with the member 83 by a spring 9I. The brake member 98 is pivoted at 92 upon the arm 11. The brake is operated by means of a pin 93 which is secured to the cam 16. A brake cam 94 is disposed on the end of the brake arm 90. When the pin 93 engages the brake cam 94, the spring 9| will be compressed to release the brake 98. It is seen therefore that rotation of the cam 16 periodically operates to release the brake 90 with respect to the contact carrying member '83. Such operation takes place as the galvanometer pointer BI is being engaged by the arm 84 to position the switch operator 93.

Mounted on the switch operator 83 is a switch member 95. The switch member 95 has an upper contact 96 and lower contact 91. The switch member 95 is secured at its lower end by means of a rivet or other suitable means to a forwardly extending arm 98 on the lower arm 81 of the switch operator 83 and is so secured to this arm 98 that the upper end of the member 95 is biased into engagement with a stop 99 extending forwardly from the switch operator 83. The contact 36 cooperates with a contact screw I08 to energize the coil 23 of the motor 20, and the contact 91 cooperates with a contact screw IN to energize the other coil 22 of said motor through circuits to be traced hereinafter.

The cam 65 which operates the clamping lever 63 is provided with a riser portion I82, a high dwell portion I03 and a low dwell portion I84. As the cam 65 rotates counter-clockwise, as indicated by the arrow in the drawing, the clam ing lever 63 is held out of engagement with the pointer M as long as the follower 66 rides on the high dwell portion I03 of the cam. As the follower 66 moves down toward the low dwell portion I04 the lever 63 is moved into engagement with the pointer M by the spring 61. The lever 63 is maintained in engagement with the pointer 6| as long as the follower 66 is adjacent the low dwell portion I04 of the cam. When the follower 66 rides on the riser portion I02, the lever 63 is moved away from the pointer 6|, thus freeing it The cam 14 which reciprocates the arm 11 through the follower 16 comprises a low portion I06, a riser portion I07, a first drop-off portion I08 of relatively short length and steep slope, a second drop-off portion. I09 of considerably greater length and less slope, and an abrupt drop-01f portion IIO connecting the portion I09 with the portion I06. The cam follower 16 is shown as just leaving its extreme left-hand position and engaging, the low portion I86. As the follower 16 moves up the riser portion I81, the arm 11 is moved rapidly to the right carrying with it the switch actuating member 83. This moves the extension 86 out of the range of movement of the galvanometer pointer 6| which is then unclamped, and moves the contacts 96 and 91 to a position wherein the stationary contacts I00 and IM may be engaged. As the follower 16 moves down the drop-off portion I08, the arm 11 is moved rapidly to the left for a short distance. As the follower 16 moves on down the slow drop-off portion I 89, the arm 71 continues to move to the left, but at a considerably slower rate. When the follower 16 reaches the abrupt drop-off portion H0, the arm 11 i moved very rapidly to the left until the follower 16 engagesthe low portion I86 of the cam 14. During the last very rapid movement, extension 84 again moves within the range of movement of the galvanometer pointer 6I which is now clamped by the arm 63.

As the cam member 16 rotates to move the contact mechanism to and from the stationary contacts and back to take a new position in accordance with the positioning of the galvano-meter needle 6|, the brake mechanism 90 is likewise operated. By the arrangement shown the brake mechanism is adapted to be released to provide for free. positioning of the contact mechanism as the contact mechanism moves to a left-hand position. At this time, the arm 88 at the upper end of the contact carrying member 83 engages the galvanometer needle 6!.

.When this operation is taking place the pin 93 carried upon the cam member 14 is in engagement with the cam follower 94 upon the brake arm 90. At this time then, the brake will be biased in a counter-clockwise direction which will move the brake shoe from the semi-circular portion of the switch operator 83. In this manner it is seen that when the switch mechanism is being positioned in accordance with the position of the galvanometer needle, the brake is released to thereby relieve the force acting upon the galvanometer needle. At this time the only force which will bias the arm 04 into engagement with the galvanometer needle will be that force exerted by the light spring 05.

Details of the construction of the strain release mechanism of the switches are shown in Figure 2. The operation of this mechanism is illustrated in Flguresii and 4. Referring now to Figure 2, the member 95 is shown as comprising a first arm I20 which extends upwardly from the bracket 98 which is bent outwardly from the lower part of the contact carrying member 83. The arm I20 is secured at its lower end to the bracket 98, The upper portion of the member 95 is formed as a neck which'supports a second arm I2I that extends downwardly toward the supported end of the arm I20. The lower end of the member 95 is so connected to the mounting member 98 that there is a bias at the upper end into engagement with the stop 99. The arm I2l is biased with a lesser force at its lower end into engagement with a stop I22. In this manner an arrangement is provided whereby the movable contacts 96 and 91 will engage the respective stationary contacts I and IOI with a given initial pressure. By such structure, the condition known as zero initial contact pressure is prevented.

Operation It may be assumed that the temperature in the space has risen to a value above that desircri, At this time the amount of resistance in the leg of the bridge including the variable temperature responsive resistance 40 will be varied. This variance in the resistance of the variable resistance 40 will result in a corresponding de ilection of the galvanometer needle (H to the left, [or example. As the galvanometer needle 6| is positioned and the contact mechanism is operated back and forth, the contact mechanism will take a position in angular relationship to the movable arm 11 which carries the cam follower I6. Hence, as the, galvanometer needle is moved toward the left the biasing spring 85 will cause the contact operator 83 to assume a position in counter-clockwise relationship with respect to the arm TI. At this time the contacts will take a position as contact 91 engages stationary contact IOI as illustrated in Figure 4, that is, the lower contact 91 will be moved closer with respect to the stationary contact IOI than the contact 96 with respect to the stationary contact I00. Hence, at this time, as the arm TI is moved toward the right; the contact 91 will engage the stationary contact WI, and as the entire contact mechanism is moved further toward the right the contact 91 will move toward the left with respect to the rest of the contact structure. At this time the arm I2I of the contact mechanism 95 will flex away from the stop I22. The bias in arm I20 is suificient to keep the upper end thereof in engagement with the stop 99. Engagement of contacts 91 and IM closes a circuit for the coil 22 as follows: From the secondary of a transformer I25, through conductor I26, contact operator 83, contacts 9'! and IOI, conductor I21, coil 22, and conductor I28 back to the transformer. The coil 22 will remain energized as long as the contacts 91 and IM are closed to move the valve in a closing direction.

As the galvanometer needle is moved to its moving arm TI. At this time the contacts when engaging the stationary contacts will take the position as illustrated in Figure 3 wherein the contact 96 is shown engaging the contact I00. Upon such engagement the upper end of the switch mechanism 95 will be bent away from the stop 99 and the lower end of the arm I2I will remain in engagement with the stop I22.

Engagement of contacts 96 and I00 closes a circuit for the coil 23 as follows: From transformer I25, through conductor I26, contact operator 83, contacts 96 and I00, conductor I29, coil 23, and conductor I20 back to the transformer. This circuit moves the valve I4 in an opening direction.

The configuration of the contact member 95 is such that approximately the same contact pressure will be obtained for each of the contacts 99 and 91. However, it will be obvious that the upper contact 99 will have a slightly greater pressure than the lower contact 91. The reason for this is that the upper end of the member 95 must be biased into engagement with the stop 99 with sufficient force to resist movement upon the bending back of the lower con tact arm I2I.

When the temperature responsive resistance located in the space II is satisfied, or when the valve has assumed a position wherein suflicient resistance is placed in series with the temperature responsive resistance so that the galvanometer needle is in its mid position, then the contact mechanism may be so arranged that as it is moved to its extreme right-hand position neither of the stationary contacts I00 or I M will be engaged. At this time, the valve I4 will retake a position in clockwise relationship to the main in its adjusted position until such time as the ambient temperature varies to affect the temperature responsive resistance 40.

Referring now to Figure 5, wherein a modification of the contact structure is shown. The contact operator 83 is identical in every respect with the contact operator heretofore referred to. Mounted on the lower mounting bracket 98 is a contact member I30 comprising an upstanding arm I3I, a neck portion I32, a lower contact arm I33 carrying a contact I34 and an upper contact arm I35 carrying a contact I36. With this structure the initial contact pressure of both the upper and lower contacts I34 and I35 may be the same, that is, the arm I 3I may be biased toward the steps 99 and I22 with a given force. Because of the novel structure in this modification both contacts will be urged into engagement with their respective stationary contacts with the same force.

As one of the contacts I34 or I36 engages its corresponding stationary contact it will be obvious that that contact will be forced back and rotate both the upper and lower contact arms around the opposite stop, that is, the stop for the other contact, and thus flex both the contact arms I33 and I35 as well as the supporting arm I 3|. As both contacts are located equally distant from the neck portion I32, this force exerted when either contact is moved by a stationary contact because of movement of the contact operator 83 will be substantially identical.

The modification shown in Figure 5 is adapted to be applied into the system as illustrated in Figure l. The operation of the device with this part provided thereto will be identical to the operation described in connection with the other form of my invention.

While I have shown two forms which my invention may take, it will be obvious to those skilled in the art that many other adaptations of 3 the device may be made. For example, it. will be obvious to combine my-m'ovelstrain release and scope of the appended 'art.

I claim as my invention: 1 1. In combination, a pair of spaced fixed electrical contacts, a pair of movablejcontacts-cooperable therewith, movable means for "oscillating said movable contacts to and'from saidstationmam ary contacts, adjustable means for positioning said movable contacts angularly withrespect to. said movable means so that one of said movable 1 contacts only may contact its cooperating Stationary contact, and strain release means ior' mounting said movable contacts comprising, a

flexible strip secured atone end, said strip havangularly adjustable member moved by said oscillatable member, and a pair or actuating means mounted upon said adjustable member comprising a flexible member, said member being formed so that one or saidactuating means may flex' away from-its first position while the other actuating "means remains in itsfirst position.

3 7. In combination, a pair of fixed spaced electrical contacts, an actuator, a U-shaped flexible contact carrying member mounted at the end of one leg upon said actuator, a first contact mounted adjacent" the bend of said Li-shaped member.

' and a second. contact mounted adjacent the end oi the second leg of said U-shaped member.

8. In combination, a pair or fixed spaced electrical contacts, an actuator, a U-shaped flexible contact-carrying member mounted at the end of one leg upon said actuator, a first contact mounted adjacent the bend of said U-shaped member,

a second contact mounted adjacent the end of the second leg of said U-shaped member, and a pair of stops adjacent said contacts, said member ing a freeend mounting the first of saidmovable contacts, a portion of said strip secured atbeing biased so that portions thereof will engage said stops with a predetermined force.

said free end and extending toward the mounted I end of said strip, the free endgof said'portion mounting said second movable contact. 1

' 2. In combination, a pair of control contacts,

an intermittently oscillatable member movable toward and away from said controlcontacts, an

angularly adjustable member moved b'y said os-E cillatabie member, a pair of actuating means mounted upon said adjustable member comprising a flexible strip mounted atone end, a first actuator at the free end thereof, a first stop to limit the movement of said free end in one direction, said free end being biased by a force into engagement therewith, a flexible member secured to said strip and extending toward said mounted end, a second actuator at the end of said flexible member, and avsecond stop to limit the movement of said last end'in one direction.

3. In combination, a pair of actuable control means, and means for intermittently actuating said control means "comprising a flexible strip mounted at one end, a first actuator at the free end thereof, a-first stop to limit the movement of said free end in one direction, saidfree end being biased by a force into engagement there with, a flexible member secured to said strip and extending toward said mounted end, a second actuator at the end of said flexible member, and

end in one direction, said last end being biased into engagement therewith with less force than v the bias of said free end.

4. A contacting device of the character described for mounting upon a support comprising, a member of flexible material mounted 0n said support at one of its ends, a first contact carried at the other end of said member, a flexible arm formed on said member and extending toward the mounted end thereof, and a second contact carried at the end of said arm.

5. In combination, a pair of fixed spaced control means, a pair of actuating means for said control means, and means connecting said actuating means comprising a flexible member, said member being formed so that one of said actuating means may flex away from its first position while the other actuating means remains in its first position. Y

6. In combination, a pair of control contacts, an intermittently oscillatabl member movable toward and away from said control contacts, an

, mined force.

9. In combination, a pairof fixed spaced elec- .trical contacts, an actuator, a flexible contact carrying member comprising, an arm mounted at one end on said actuator, a neck portion atthe free end of said aringan elongated portion extending substantially equidistant in opposite directions,,from said neck portion and' a pair of contactsycarried near the'ends of said elongated p0rti0ii. .f.' f

10, In combination, a pair of fixed spaced electrical contacts, an actuator, a flexible contact carrying member comprising,--an arm mounted at one end on said actuator, aneck portion at the free end of said arm, an elongated portion extending substantially equidistant in opposite directions from said neck portion, a pair of contacts carried near the ends of said elongated portion,-and a pair of stops adjacent said contacts, said member being biased so that portions thereof will engage said stops with a predeter- 11. The combination comprising a support, an

actuating membermounted on the support and movable from a first to a second position, an adjustable member mounted on thesaid actuating member, a first pair of electrical contacts mounted on the support, a switch member mounted on the said adjustable member, a second pair of electrical contacts mounted on the switch member at opposite nds thereof for cooperation, with the first pair of electrical contacts, a pair of stops mounted on the adjustable member for limiting the movement of the switch member in one direction, spring means normally biasing the switch member into contact with the stops, means for pivotally adjusting the adjustable member so as to vary the position of the second pair of contacts in relationship to the first pair of contacts so that upon movement of the actuating member from the first to the second position one of the second pair of contacts only may contact in engaging relation its cooperating contact in the first pair of contacts, and the said spring means holding the engaging contacts under spring tension.

12. The combination comprising a plurality of actuable control contacts, a movable member, biasing means for the said member, means limiting the movement of the member in response to the said biasing means, means carried by the said member for actuating the said control contacts.

and adjustment means for varying the position or the movable member in relation to said contacts so that one or said actuable control contacts only may be actuated by said actuating means.

13. The combination comprising a plurality of spaced electric contacts, a member for engaging the said contacts, adjustment means for varying the position of the member so that said contacts may be selectively engaged by the member at 10 opposite ends of said member, means for moving the said member in relationship to the contacts, and the member movable at one end in one direction upon engaging one of said contacts, and means limiting movement 01' the opposite end of said member responsive to the biasing effect of said one contact in such a manner as to prevent the engagement of said contacts by the opposite end of said member.

BENJAMIN CYR. 

